module.exports = function (app) {
    let context = app.context;
    context.ok  = function (msg = "ok") { // can not use '=>', due to 'this'
        this.status  = 200;
        this.message = msg;
    };
    context.bad = function (msg = "invalid parameters!") { // can not use '=>', due to 'this'
        this.status  = 400;
        this.message = msg;
    };
};